How do you use a tubular inside micrometer?

2nd March 2020


How to use a tubular inside micrometer


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		When taking internal measurements, you may need to use an extension rod if the measuring capacity of your micrometer is not great enough.

		To select the correct extension rod, insert each of the rods provided with your micrometer into the instrument and hold them inside the space to be measured.

		The correct rod will be the largest one that can be fitted into the hole or opening.

		Step 1 – Zero micrometer When you have determined which rod to use and have attached it to the end of the micrometer, turn the thimble until the micrometer reads zero.

		Step 2 – Insert micrometer Insert the micrometer into the opening you are measuring.

		Step 3 – Rotate thimble Turn the thimble using the ratchet speeder until the spindle is close to the object. As you approach the edge of the hole, pivot the micrometer, keeping it square. Continue turning until the spindle stops rotating. The ratchet will keep turning, applying the correct amount of force for an accurate measurement. Using the thimble alone requires a degree of skill and practice to achieve the correct “feel”.

		Step 4 – Turn locking device Turn the lock nut to secure the distance between the measuring faces so that you can remove the micrometer. To acquire the actual measurement of the inside diameter or expanse, add the size of the extension rod to the measured value indicated on the micrometer scale. See How to read a metric micrometerfor additional information on reading the scale.